Western Australia was the largest of the colonies and remains as such today.
Originally excluded from the new colony of New South Wales proclaimed by Lt. James Cook on behalf of the British in 1770, the entire portion of the Australian continent that we know as Western Australia today, remained as “New Holland ” from Longitude 135o E, westward until the year of 1825, when the border was moved a little further westward to 129o E . . .
Captain Charles Howe Fremantle received orders to secure the west coast of New Holland in preparation for the arrival of British settlers and their possessions. He and his crew set sail on the HMS Challenger on the 10th March 1829. Arriving and anchoring off Garden Island on the 2nd May 1829, he proclaimed the entire area of New Holland, westward of Longitude 129o E, in the name of His Majesty the King, naming it the “Swan River Colony”.
The Swan River Colony remained so named until the 6th February 1832, when it was officially renamed “Western Australia”.